1. Field of the Invention
The present invention relates to a lens cap device and, more particularly, to a lens cap device that incorporates a thin lens cap and uses an actuating device to control the fast slide motion of the cap lens, so as to facilitate lens protection.
2. Description of Related art
Projectors use projection lenses to project data image to external receptacles such as screens. Once the projection lenses are scratched or contaminated by dusts, the imaging quality of projectors is seriously affected. Therefore, the projector is typically equipped with a lens cap to protect the lens from being scratched or contaminated. The lens cap is externally attached to the projector and needs to be removed from the projector before switching on the projector. It is thus very easy to lose or misplace the lens cap, hence causing much trouble for users. Moreover, the projector is turned on before the lens cap is removed, the high temperature of the projection light causes the lens cap which is generally made of plastic to be melted and result in safety issue. In order to resolve the misplacement problem, the lens cap is typically connected to the enclosure of the projector by a string, which degrades the aesthetic effect of the projector without resolving the safety concern.
In another conventional design, the lens cap is attached to external side of a housing of the projector. The lens cap is slide or turned to open or close. In either way, the lens is exposed outside of the projector to affect the aesthetics of the projector.
In yet another conventional design proposed in Taiwanese Patent No. 512255, an electric lens cap is driven to open or close by gears and belts of a step motor controlled by electric power. This technique often suffers from inaccurate actuation because of mechanical jamming caused by dusts and the lens cap cannot be properly open or close. Further, the internal high temperature of the projector often dries up or cause leakage of lubricating oil, which also affects operation of the lens cap. Furthermore, the electrical approach is costly and inconvenient that the lens cap cannot be removed until the electric power turning on.
In consideration of the above drawbacks in operation and structure design of the prior art, a lens cap device is provided to provide more convenient operation and improved safety.